Comparative Analysis of Metagenomic Next-Generation Sequencing and Conventional Culture for Pathogen Detection in 218 Patients with Pulmonary Infectious Diseases: A Retrospective Study.

BACKGROUND: Metagenomic next-generation sequencing (mNGS) is a promising technique, but comparative studies of mNGS and culture across different pulmonary diseases are limited. METHODS: We retrospectively analyzed data from 218 patients who underwent BALF mNGS testing between November 2021 and April 2025, and patients were categorized into pneumonia, bronchiectasis, NTM, tuberculosis, and other groups based on discharge diagnoses. We compared detection rates, pathogen spectra, co-infection rates, and special pathogen distributions between mNGS and culture. We also assessed concordance (Kappa) and complementary rates. RESULTS: The overall positive detection rate of mNGS was significantly higher than that of culture (95.4% vs 67.4%, P<0.001). The overall concordance rate was 71.1%, with a Kappa of 0.42. mNGS additionally detected pathogens in 84 cases (38.5%), primarily viruses (38), Nocardia (8), NTM (15), fungi (45), and Legionella (4). Culture additionally detected 23 cases (10.6%). Co-infection was detected by mNGS in 118 cases (54.1%), far higher than culture (42 cases, 19.3%, P<0.001). The bronchiectasis group had significantly higher detection of Pseudomonas aeruginosa (54.5%) and Nocardia (18.2%). CONCLUSION: mNGS provides a higher detection rate than culture in this cohort, particularly for special pathogens, and is complementary to culture. Pathogen profiles varied across disease types; however, the clinical benefit of mNGS-guided therapy remains to be evaluated in prospective studies.